connex 3300 hp

[wilson04]

My friend has a connex 3300 hp that will not transmit. When you key up all you hear is a one click. (The mic keying up) The meter doesn't move and nothing else comes out audio wise. The recieve seems to be working okay. Any ideas where to look first? Thanks.

 

[Robb]

The mic or the antenna is 90% of most radio problems - according to some techs. I would test the mic out thoroughly and use another known working mic first. Connex uses the same 4-pin mic wiring as Cobra, Galaxy, Ranger, and Magnum. So, it shouldn't be too difficult to eliminate this area first.

Let us know how that works out - or if it requires a next step...

 

[wilson04]

I have tried another mic and that doesn't seem to be the problem. I have also tried it on a dummy load as well as in a semi and I get the dame results. I don't have any history on the radio, it came in a semi that he had bought. It has (2) 2312 finals in it and it looks to have been P/T and one point in time.

 

[wilson04]

I think I have a short somewhere. I can barely here the talkback but it is working. The meter still doesnt move and the TX light stays green. It did come on red for about 3sec one time and the tx sounded good. Any ideas how or where to check the mic wires in the radio?

 

[Robb]

The most common problem with any mic are the wires inside the mic plug. From what you've described - working for a moment and then not working, that sounds like the problem to me. I break those little wires inside the mic's plug every few months or so - and have to resolder them.

 

[Radio Tech]

Sounds like a simple problem since the TX led does not light.

With the front of the radio facing you and the solder side up look at the left side rail. About middle way there is a transistor bolted the the side rail. This is TR41 and is a 2SA473. This is the 8 volt regulator. The first thing to do is inspect the 3 pins and see if the solder traces are cracked. Flex the side of the radio to be sure.

If you do not see a crack work your way towards the front of the radio looking for bad solder connections. You will see 3 transistors in the front corner, 2 are A1012 and a C945. If still no bad solder connections, Well, look again.

After you have verified that then check the regulator (TR41). On the collector (center pin) you should have around 8 volts.

Also sometimes D77 opens. This is a diode under the mic jack. It is black with a yellow stripe.

 

[wilson04]

I have checked TR41 and everthing looks good. I have 8v on the collector (center) and the traces look to be good. I went and touched up the solder connections and they all look good in that area. I now have quiet talkback with echo but the meter still doesn' move. The TX light still stays green also when I key up and talk. I also don't have any static on AM either when the squelch is fully counter-clockwise. I do have static on FM though. The diode in D77 is also OK. What else can I check or did I miss something else?

 

[Radio Tech]

Check the two 2SA1282's up front by the mic jack.

 

[wilson04]

TR36 has 8V on all 34 legs. TR38 8V on two outside legs and 0V on center leg.

 

[wilson04]

Opps. TR36 8V on all 3 legs

 

[Radio Tech]

Thanks for the clarification! 8 pins lol

Check TR38

Base
8.03�RX�
7.75�TX

Collector
0.00�RX�
8.37�TX

Emiter
8.55

TR36
Base
7.80

Collectoer
8.52�RX
0.00�TX

Emiter
8.55

 

[wilson04]

I just checked them.

TR38
Base- 7.75
Collctr-0
Emittr-8.5

TR36
Base-7.75
Collctr-8.25
Emittr-8.5

I double checked the values of the transisters on the board. It seems my values are opposite of what you stated. Tr38 has Tr36 values
& TR36 has TR38 values??????

 

[wilson04]

Those values are all on TX. I dont have any way to inject a signal for receive.

 

[Radio Tech]

The voltages I posted are tx and rx. No signal injected.

 

[wilson04]

Okay. I went through and tested them again. Here's what I got.

TR38
Base RX 8.0
TX 7.8

Coll. RX 0
TX 0

Emitt 8.5

TR36
Base 7.8

Coll. RX 8.5
TX 8.5

Emitt 8.5

Hope this helps a little more. Thank you for all the help by the way.